<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>第49个CSS页面</title>
</head>
<body>
<!--负外边距-->
<div style="height: 100px; margin-bottom: -75px; width: 50px; background-color: red;">C</div>
<div style="height: 100px; margin-top: -50px; margin-left: 50px; width: 50px; background-color: green;">D</div>
<p>参与折叠的外边距均为负值</p>
</body>
</html>